1. Technical Field
The present disclosure relates to a lamp unit installed to a headlamp of a vehicle.
2. Background Art
Known lamp units of this type are provided with a component known as a rotary shade. A rotary shade is a component with a rotation axis that extends in a vehicle left-right direction, and plural light blocking plates with mutually different end edge shapes are provided at different angle positions around the circumferential direction (see, for example, JP-A-2011-5992).
The rotary shade is rotated about the rotation axis to provide one of the plural light blocking plates on a light path between a light source and a projector lens. A portion of light emitted by the light source is thereby blocked, and the shape of an end edge is projected through the projector lens to the front of the vehicle. A portion of a peripheral edge of a light distribution pattern formed in front of the vehicle has a shape corresponding to the shape of the end edge. By selecting one of light blocking plates that are disposed on the light path, plural light distribution patterns can be formed selectively using a single light source.
Known plural light distribution patterns include low beam patterns that illuminate a short distance ahead so as not to give glare to vehicles ahead, and high beam patterns that illuminate a broad range far ahead. Moreover, light distribution patterns are known that can both suppress glare and secure forward visibility in a high beam illumination state by forming a shadow region for only regions ahead where a vehicle or a pedestrian have been detected. In the present specification, such light distribution patterns are referred to as “partial high beam patterns”.
As described in JP-A-2011-5992, a left side partial high beam pattern is formed with an upper right portion of the high beam pattern of the left headlamp as a shadow region, and a right side partial high beam pattern is formed with an upper left portion of the high beam pattern of the right headlamp as a shadow region. The partial high beam pattern described above can be formed by superimposing these light distribution patterns. The position and size of the shadow region can be changed by performing swivel control to turn the optical axis of the lamp unit in the left-right direction.
Rotary shades are known that are provided with a twisted end edge that extends about the rotation axis so as to connect together different positions along the rotation axis direction (see, for example, JP-A-2010-232081). The twisted end edge is projected as the boundary of a shadow region partially formed within a high beam pattern. The rotation axis direction position of the twisted end edge changes in response to rotation of the rotary shade. The position of the boundary with the shadow region, namely the position and size of the shadow region, can thereby be changed according to the positions of vehicles, pedestrians and the like ahead that are not to be illuminated.
A peripheral face extending around the rotation axis of the rotary shade is needed in order to form the twisted end edge. In order to increase the movement range of the boundary with the shadow region in response to the rotary shade rotation, the incline of the straight line that joins together the “different positions along the rotation axis direction” in an opened-out view of the peripheral face may be brought closer to a direction running parallel to the rotation axis.
However, the incline of the twisted end edge that is employed in projection is lessened, and the boundary with the shadow region becomes indistinct. Moreover, the amount of light projecting toward the projector lens that is blocked by an end face of the rotary shade that includes the twisted end edge increases, with the brightness in the vicinity of the boundary thereby being lowered.